The pet industry has provided a wide range of offerings of treat products for dogs over the years. These include synthetic products such as those composed of nylon, rubber, rope or other materials that can be manufactured into a shape of interest to the animal. For the most part this type is considered a non-consumable pet toy. Another type of product includes a consumable treat with a short chew-time such as for example, jerky style products, dog biscuits or extruded kibble pieces. Another alternative is a consumable chew with a long chew-time such as knotted or rolled rawhide products, dehydrated body parts or injected molded treats where an edible fraction is injected under heat and pressure into a three dimensional mold and then solidified and dehydrated.
Several attempts have been made for improving the palatability of pet chews to pets and consumer appeal of pet chews. Some pet food manufacturers have developed products having flavor or palatability enhancers which are applied to the surface of dry dog and cat foods to increase palatability. These products were produced primarily with chicken viscera fraction with other more flavorful meat fractions such as beef liver, chicken liver or mechanically deboned beef and pork fractions. U.S. Pat. No. 3,119,691, for example, discloses dry animal food capable of forming a gravy-containing mixture on addition of aqueous liquid wherein the mixture comprises a particulate mass of a gelatinized expanded farinaceous material and a layer of solid fat.
Enzymes have been utilized in the pet ingredient preparation field to liquefy meat product fractions for further processing into usable pet food or pet treat ingredients. U.S. Pat. No. 3,578,461 teaches the use of protease enzymes to liquefy poultry feathers for further use in an animal feed product. U.S. Pat. No. 3,930,031 disclosed a synergistic flavor enhancing coating for cat food compositions comprising citric and phosphoric acids. U.S. Pat. No. 4,229,488 discloses a process for coating biscuit type products with an emulsified liver fraction to produce a more palatable product and improved appearance of the end biscuit. U.S. Pat. No. 4,366,175 discloses biscuit or kibble products coated with glazed liver. U.S. Pat. No. 4,508,741 teaches a unique coating for biscuit type products which combined a mixture of a farinaceous material and a small amount of proteinaceous material to supply an improved flavor and a sheen to the surface of the biscuit. U.S. Pat. No. 4,822,626 by Nabisco Brands relates to a dog biscuit with a baked-on proteinaceous coating. Nabisco disclosed further advancement of the technology to produce coated baked canine biscuits in U.S. Pat. No. 5,532,010.
Several of the above-mentioned technologies relate to the use of coatings on pet food products. In recent years, there has been a significant increase in the interest in treats with an extended chew-time of hours and days compared to the chew time of seconds for biscuit or jerky style treats. The difficulty faced by researchers when dealing with long chew-time treats is that these products are non-porous and liquid based coatings will not penetrate or even pass by capillary action from the surface of the treat to the inside. Thus it is difficult to provide a mechanism where a portion of the coating matrix can penetrate the surface of a pet chew to provide for permanent attachment. This is especially observed for coatings on hard surfaces such as bones. To compound this problem, the surface of pet chew is often too greasy or oily to allow for firm attachment of a coating to the surface. Therefore, despite several different approaches to enhance palatability and appeal of pet chew products, there is still a need for improvement. The present invention thus contemplates a safe, palatable and long-lasting chew product which provides a pet chew product having improved palatability and consumption time.